Work

Ion Exchange Membrane-like Deposited Electrodes for Capacitive De-Ionization: Performance Evaluation and Mechanism Study

Year: 2025

Type: article

Abstract: Capacitive de-ionization (CDI) holds great promise for water desalination, while the widely used activated carbon (AC) electrodes suffer from a low salt adsorption capacity (SAC) and poor long-term stability due to the co-ion effect and electrode oxidation. Inspired by membrane-based CDI, we deposited polyethyleneimine (PEI), an ion exchange polymer with positive charge and ion selectivity, onto an AC electrode to serve as an anode for addressing these issues. Firstly, compared to traditional AC and commercial AEM-AC, the PEI-doped AC (PDAC) anode delivered a superior SAC of 36.3 mg/g, as the positively charged PEI enhanced electrostatic attraction, suppressed the co-ion effect, and offered extra sites. However, it showed poor cycling stability with 77.1% retention, owing to mass loss and anode oxidation. We further developed an electrode coated with a PEI-based membrane (PMAC), which exhibited a balanced performance with a high SAC of 33.4 mg/g and significantly improved long-term retention of 97.5%. The hydrophilic PEI membrane, strongly adhered to the AC surface, shortened the ion diffusion resistance and effectively prolonged the electrode lifespan. A systematic comparison between AC, AEM-AC, PDAC, and PMAC revealed the mechanism for PMAC's notable enhancement. These findings establish a framework for designing novel CDI electrodes and advancing sustainable water desalination.

Source: Membranes

DOI: 10.3390/membranes15110338

Authors: Siyue Xue, Chengyi Wang, Tianxiao Leng, Chenglin Zhang, Long-Fei Ren, Jiahui Shao

Institution: Shanghai Jiao Tong University

Language: English

Topic: Membrane-based Ion Separation Techniques

Subfield: Biomedical Engineering

Field: Engineering

Domain: Physical Sciences

SDGs: Clean water and sanitation, Affordable and clean energy

Open Access status: gold

Estimated APC paid: $2,654